The present invention relates to vehicle seats, and particularly relates to vehicle seats to reduce the impact at the time of a rear-end collision.
In general, when a vehicle such as an automobile experiences a rear-end collision by being rear-ended, a large impact when traveling in reverse, or the like, there is a risk that the head region of an occupant sitting in a seat in the vehicle will snap backwards suddenly due to inertia force, resulting in an impact on the neck region.
For this reason, vehicle seats in automobiles and the like have conventionally included headrests in the upper area of the seat backs that support the heads of occupants from behind in order to protect the head regions, neck regions, and the like, of occupants from impacts caused by rear-end collisions, thereby reducing impact on the neck regions of the occupants.
However, simply providing a headrest cannot reduce impacts on the body, and furthermore, if the gap between the head region of the occupant and the headrest cannot quickly be reduced at the time of a rear-end collision, there may be the cases where the impact upon the neck region cannot sufficiently be reduced.
In order to solve this problem, a technique in which the headrest is caused to move forward at the time of a rear-end collision due to the backward moving load of the occupant, thus supporting the head region of the occupant and reducing the impact on the neck region, has been proposed (for example, see Japanese Patent Application Publication No. 2003-341402 (“the '402 Publication”)).
In addition, a technique in which, in a vehicle seat provided with a seat back that supports a seat back cushion using a seat back frame, the area of the seat back that makes contact with the back of the occupant at the time of a rear-end collision has a lower spring coefficient and a higher damping coefficient than those of the other areas, is known (for example, see Japanese Patent Application Publication No. 2005-028956 (“the '956 Publication”)).
Furthermore, a vehicle seat has been proposed in which, in a backrest that includes a headrest, a mobile frame having a spring member that supports a cushion member is attached to a fixed frame on the top of which the headrest is mounted so that the upper portion of the mobile frame rotates backward along the lower portion of the mobile frame; furthermore, a spring that supports a normal seating load but allows the mobile frame to move backward when an impact load greater than or equal to a predetermined load is exerted thereon is provided between the fixed frame and the mobile frame (for example, see Japanese Patent Application Publication No. 2000-272395 (“the '395 Publication”)).
Further, a technique that moves a headrest to a support position corresponding to a predicted rear-end collision by a continuous adjustable positioning system for adjusting the position of a headrest continuously is known (for example, see Japanese Patent Application Publication No. 2005-177227 (“the '227 Publication”)).
Although both of the techniques disclosed in the '402 and '956 Publications soften the impact on an occupant, the technique disclosed in the '402 Publication receives the backward movement of the chest area of the occupant with a pressure receiving member at the time of a rear-end collision, and causes the headrest to move forward along with the backward movement of the pressure receiving member. With such a technique, it is necessary to provide a separate movement mechanism for the headrest in order to allow the tandem movement with the headrest, which complicates the mechanism and increases the cost thereof. Furthermore, because it is necessary to provide a mobile portion in the seat back frame in order to move the headrest, it is also necessary to prevent a resulting rigidity degradation of the structure. Therefore, an increased rigidity beyond what is normally required is necessary.
The technique disclosed in the '956 Publication increases the backward movement of the upper body and decreases the relative amount of movement between the head region and the back region by reducing the spring coefficient of the area that makes contact with the back region of the seat back (the “chest region” in the '956 Publication), and, by increasing the damping coefficient by way of a cushion of low rebound resilience, reduces the shearing force that acts on the neck region by suppressing rebounding of the upper body and reducing the relative speed between the head region and the back region.
However, with a technique that reduces the spring coefficient, a technique that employs a cushion of low rebound resilience, or the like, there has been a problem in that the amount by which the body sinks toward the back of the vehicle (in other words, the amount of movement) cannot be increased.
Furthermore, the technique disclosed in the '395 Publication simply sets the elastic force of the spring relative to the impact load, and thus the operational load at which a central support portion moves backward can reliably be predicted, ensuring that that portion moves backward without fail. This technique thus has an advantage of ensured operations.
However, with the technique disclosed in the '395 Publication, the fixed frame and the mobile frame are fixed at their lower portions using an attachment shaft, and thus there is a quite small movement of the mobile frame allowed relative to the fixed frame in the vicinity of the lower areas thereof. So, there is a problem in that the entire body of a seated occupant cannot be caused to sink toward the back of the vehicle. Furthermore, the spring disclosed in the '395 Publication experiences a reaction force increase along with an increase of the amount of movement, which disturbs the movement. Furthermore, the range of mobility between the fixed frame and the mobile frame is extremely limited, and there has thus been a problem in that it is difficult to ensure a movement amount that allows a high degree of sinking. Furthermore, because the mobile frame is used, the overall size of the apparatus increases and achieving a lighter weight is difficult.
In addition, with the technique that moves the headrest by attaching the pressure receiving member to the seat frame with a wire, because the posture of the occupant is held by the pressure receiving member and because the headrest is moved by way of loads exerted on the pressure receiving member, it is necessary to prevent deformation of the wire serving as the coupling member to the greatest extent possible. However, because the wire does not deform, the amount of sinking is reduced and this makes it difficult to increase the amount of movement while achieving a balance with seating comfort.
The technique disclosed in the '227 Publication makes it possible to move the headrest to a support position in accordance with a predicted rear impact, which is effective in preventing whiplash injuries. Furthermore, the mechanism, which includes a motor, is provided within the headrest and thus the elements that need to be provided within the vehicle seat itself can be minimized.
However, if the expected functions against a rear impact are to be attained using a single neck region impact reduction apparatus, such as an active headrest unit, it is necessary to increase the amount of movement of the headrest. However, if the amount of movement of the headrest is increased and the headrest is moved by the increased amount to a head region receiving position in a short amount of time, there may be a problem that a sense of discomfort will be imparted upon the occupant, depending on the position of the head region of that occupant.
Furthermore, there is a problem in that, if an attempt is made to increase the amount of movement, it is necessary to provide a corresponding mechanism in the headrest, which leads to an increase in the weight thereof.
Thus, what is needed is a technique that can reduce the amount of movement of the headrest, move the headrest with a small apparatus, and realize a more highly-safe impact reduction function against rear impacts in a highly-responsive and reliable manner.
It is an object herein to provide a vehicle seat that, using a simple configuration that is independent from a headrest, can increase the amount of sinking (movement) of the entire body of a seated occupant toward the rear of the vehicle at the time of a rear-end collision, and can reduce the impact on the occupant at the time of a rear-end collision.
It is another object herein to provide a vehicle seat that suppresses malfunction of an impact reduction member because of the impact reduction member that does not easily move during normal seating, while also ensuring smooth movement of the impact reduction member after the movement at the time of a rear-end collision.
It is yet another object herein to provide a vehicle seat that effectively reduces impacts on the body, the neck region, and the like, of an occupant at the time of a rear-end collision, using a configuration that does not require rigidity beyond what is normally required, with a lower number of components, a small size, a light weight, a simple structure, and a low cost.
It is yet another object herein to provide a vehicle seat that effectively provides rigid side portions with impact reduction members that move independently from headrests in order to reduce the impact on the neck region and the like of an occupant at the time of a rear-end collision, and that prevents interference with other members that are provided.
Furthermore, it is yet another object herein to provide a more highly-safe vehicle seat that reduces the size of a neck region impact reduction apparatus at the time of rear-end collisions and that reliably realizes an impact reduction function against rear impacts in a highly-responsive and reliable manner.
The problems mentioned above are solved by a vehicle seat including: a seat back frame including at least side portions located on both sides of the seat back frame and an upper portion disposed in an upper area of the seat back frame; a headrest disposed in an upper area of the seat back frame; a pressure receiving member that is linked to the seat back frame via a coupling member and that moves independently from the headrest; and an impact reduction member that is disposed in at least one of the side portions of the seat back frame, is linked to the pressure receiving member, and moves independently from the headrest under a predetermined impact load. The impact reduction member is linked to a biasing element that biases the pressure receiving member toward a front of the seat back frame via the coupling member; and the force that restores the impact reduction member into an initial state is greatest during normal seating, and covers a range in which the force decreases when the impact reduction member moves due to a rear-end collision.
As described above, the force that restores the impact reduction member into the initial state is greatest during normal seating, and thus the impact reduction member does not easily move during normal seating, malfunction of the impact reduction member is suppressed, and the impact reduction member is stabilized. Furthermore, because the force that restores the impact reduction member into the initial state covers a range in which the force decreases when the impact reduction member moves due to a rear-end collision, the impact reduction member smoothly moves at the time of a rear-end collision within that range. This makes it possible to significantly move the pressure receiving member that is linked to the impact reduction member and cause the occupant to sink into the vehicle seat.
Furthermore, because the impact reduction member is linked to the biasing element that biases the pressure receiving member toward the front of the seat back frame via the coupling member and because the pressure receiving member moves independently from the headrest, the impact reduction member can move under a load from the pressure receiving member at the time of a rear-end collision, and thus the head region of the occupant is caused to come into contact with the headrest in a state where the body of the occupant is kept in a seated posture. For this reason, it is possible to reduce impacts on the head region or the neck region by supporting the head region of the occupant, without providing a mechanism linked with the headrest to cause the headrest to move forward.
Furthermore, because the impact reduction member and the pressure receiving member are both independent from the headrest, a mechanism or the like for transmitting loads occurring at the impact reduction member and the pressure receiving member to the headrest is not necessary. This enables a simply designed vehicle seat with a lighter weight.
In an embodiment, the impact reduction member includes a shaft that is rotatable, and for the momentum generated by the biasing element that causes the impact reduction member to rotate to be greatest during normal seating and to cover a range in which the momentum decreases when the impact reduction member rotates due to a rear-end collision.
In this manner, by employing a configuration in which the impact reduction member rotates, at the time of a rear-end collision, the impact reduction member can move smoothly, the pressure receiving member is caused to move significantly, and the occupant can reliably sink significantly. Further, the impact reduction member is configurable in a compact manner.
In an embodiment, the force that restores the impact reduction member into the initial state gradually decreases along with movement or rotation of the impact reduction member.
By doing so, because the force that restores the impact reduction member into the initial state decreases along with movement or rotation of the impact reduction member, the impact reduction member can move or rotate efficiently even when the load transmitted from the pressure receiving member at the time of a rear-end collision becomes small, and thus a sufficient amount of sinking is ensured.
In an embodiment, the impact reduction member is disposed in both of the side portions in the seat back frame, and both of the impact reduction members move or rotate independently from each other.
In this manner, by providing the impact reduction members in both the side portions in the seat back frame, simplicity and a lighter weight is achievable, which is different from the prior art in which the impact reduction member is linked to the headrest.
Furthermore, by employing a configuration in which both impact reduction members move or rotate independently from each other, in the case where an imbalance has occurred in the load, the respective impact reduction members move or rotate independently from each other in the respective side portions in accordance with the load. For this reason, the vehicle seats are settable so that sinking occurs in accordance with the size of the impact load. Further, because the force that restores the impact reduction members into the initial state decreases along movement of the impact reduction members, this configuration is advantageous in that the impact reduction members that are independent from each other can move more smoothly even solely.
In an embodiment, in the case where one end of the biasing element is linked to the seat back frame and the other end of the biasing element is linked to the impact reduction member, and a straight line that connects a position at which the seat back frame and the biasing elements are linked with the position at which the impact reduction member and the biasing elements are linked approaches the shaft, along with rotation of the impact reduction member due to the pulling force of the coupling member occurring due to a load exerted on the pressure receiving member, the position where the engagement portion of the biasing elements or the coupling member is disposed can more freely be selected.
Generally speaking, the pulling load (warp amount) of the biasing element is greatest when a line that connects the shaft with both ends of the biasing element is straight. However, in the case where the tension generated via the coupling member when the impact reduction member begins to rotate and the tension generated until the rotation is stopped (i.e., until the rotation ends) are approximately the same amount, the movement amount of the biasing element (the amount of distance change) decreases approximately when the impact reduction member is rotated by the amount it reaches the point immediately before the above-mentioned point where the load of the biasing element is greatest, i.e., the point where the trajectory traced by the end of the biasing element attached to the impact reduction member is farthest from the other end of the biasing element, and thus a region where the amount change in the pulling load of the biasing element becomes small relative to the movement position or rotational angle is created.
For this reason, the force by which the biasing element causes the impact reduction member to rotate is greatest initially and decreases along with the rotation. This results in a state where the impact reduction member does not easily rotate during normal seating but smoothly moves at the time of a rear-end collision, which is the most preferable.
Furthermore, even in a case where the tension increases due to the position at which the biasing element is disposed, the configuration is such that a straight line that connects the position at which the seat back frame and the biasing elements are linked with the position at which the impact reduction member and the biasing elements are linked approaches the shaft, which increases the region in which the biasing elements and the like are disposed. This increases the choices for the disposal of the biasing elements or the coupling member.
As described above, in the case where a large impact load has occurred due to a rear-end collision or the like, the impact reduction member moves or rotates against the biasing force of the biasing elements, thus moving the coupling member, which in turn causes the pressure receiving member to move in the backward direction, and this makes it possible to cause the occupant to sink toward the rear of the vehicle.
By employing such a configuration, the impact reduction member does not move or rotate in a load range that occurs under a normal seating load, and there is thus no effect on the seating comfort, which makes it possible to maintain favorable seating comfort. Furthermore, the force by which the biasing elements restores the impact reduction member into the initial state against the force that moves or rotates the impact reduction member is greatest initially and decreases along with the movement or rotation. This results in the state where the impact reduction member does not easily rotate during normal seating but moves smoothly at the time of a rear-end collision.
In an embodiment, the seat back frame includes a lower portion disposed in a lower area, and the impact reduction member is disposed within a range enclosed by the seat back frame.
In this manner, because the impact reduction member is disposed within a range enclosed by the seat back frame, the portion of the seat back corresponding to the lower- to mid-back region of the occupant is moved significantly backward when an impact has occurred, without interference with the various elements disposed on the outside of the seat back frame. This makes it possible to cause the occupant to sink to a sufficient extent.
In an embodiment, the impact reduction member is disposed in a range that is below the upper end of the pressure receiving member.
This makes it possible to efficiently transmit the load from the pressure receiving member that supports the body of the occupant to the impact reduction member. Thus, the portion of the seat back corresponding to the lower- to mid-back region of the occupant is moved significantly backward when an impact has occurred, and the occupant is caused to sink to a sufficient extent.
In an embodiment, the seat back frame includes a pipe portion that spans across the side portions and the upper portion, and a reclining mechanism has a rotation shaft, and the impact reduction member is disposed between a lower end of the pipe portion and the rotation shaft of the reclining mechanism.
With this configuration, the impact reduction member can effectively be disposed in the side portions having rigidity, and the impact reduction member is disposed in a position where the amount of sinking is large, so that the load can efficiently be transmitted. Accordingly, the portion of the seat back corresponding to the lower- to mid-back region of the occupant is moved significantly backward when an impact has occurred, and this makes possible to cause the occupant to sink to a sufficient extent.
In an embodiment, the impact reduction member is disposed at a height that is within a range from 50 mm to 270 mm above the hip point. The height range of 50 mm to 270 mm from the hip point is a location in which, taking the body type of the occupant into consideration, the occupant sinks the most at the time of a collision. The load on the impact reduction member is transmitted efficiently in this range, which makes it possible to sink the lower back region to the back region of the occupant into the seat back to a sufficient extent upon receiving an impact.
In an embodiment, a disposal range for an airbag apparatus is formed in the side portions of the seat back frame, and the impact reduction member is disposed between the upper end and the lower end of the disposal range for an airbag apparatus.
With this configuration, interference with other disposed elements is preventable, and the impact reduction member is disposed using the small space more effectively.
In an embodiment, a recess portion is formed in the pressure receiving member in an area that opposes the seat back frame, and the impact reduction member is disposed in a location that opposes the recess portion of the pressure receiving member.
With this configuration, because the recess portion is provided, the impact reduction member is checkable when and after it is assembled and when the skin material is opened.
In an embodiment, the vehicle seat includes a first neck region impact reduction apparatus and a second neck region impact reduction apparatus movable independently from each other; and the configuration is such that the first neck region impact reduction apparatus is an active headrest that moves the headrest forward upon the prediction of a collision or under a predetermined impact load, and the second neck region impact reduction apparatus is the impact reduction member that causes the pressure receiving member to sink toward the back of the seat back frame under a predetermined impact load.
In this manner, two types of neck region impact reduction apparatus, i.e., the active headrest and the impact reduction member are used. Thus, the two neck region impact reduction apparatuses operate independently from each other, in a manner that the headrest moves forward upon the prediction of a collision or under a predetermined impact load and that the impact reduction member causes the pressure receiving member to sink toward the back of the seat back frame under a predetermined impact load. This makes it possible to reduce the amount of operation of the respective apparatuses compared to when the apparatuses are used solely, which in turn improves the response and realizes a higher degree of safety.
In an embodiment, the first neck region impact reduction apparatus and the second neck region impact reduction apparatus have different thresholds for impact loads under which to operate.
Setting different thresholds for the loads under which the first neck region impact reduction apparatus and the second neck region impact reduction apparatus operate in this manner makes it possible to operate only one of the neck region impact reduction apparatuses, such as the second neck region impact reduction apparatus, or operate the multiple neck region impact reduction apparatuses, depending on the size of the predicted impact load or the actual collision load.
In an embodiment, the first neck region impact reduction apparatus and the second neck region impact reduction apparatus are set to have different operation start timings.
This makes it possible to set the operation starting timings to operation timings that facilitate suppression of a sense of discomfort imparted on the occupant. This in turn makes it possible to further reduce a sense of discomfort caused by multiple neck region impact reduction apparatuses operating simultaneously.
Note that a combination in which one neck region impact reduction apparatus begins to operate when a collision has been predicted and one neck region impact reduction apparatus begins to operate under a predetermined impact load, a combination in which the respective neck region impact reduction apparatuses are set to operate under different impact loads and the operation start timings differ depending on the size of the impact loads, and the like can be given as examples of the multiple neck region impact reduction apparatuses that have different operation start timings.
In an embodiment, the operation of the second neck region impact reduction apparatus is performed before the operation of the first neck region impact reduction apparatus when a predetermined impact load has occurred.
In this manner, the impact reduction member serving as the second neck region impact reduction apparatus operates first when a predetermined impact load has occurred, which causes the body of the occupant to sink significantly first, and thereafter, the active headrest serving as the first neck region impact reduction apparatus is operated. Thus, the head region of the occupant is reliably supported. Accordingly, the amount of movement of the headrest is reduced, which makes it possible to move the headrest into a head region receiving position in a short amount of time. Furthermore, because the amount of movement of the headrest is reduced, a compact headrest is realizable without increasing the size of the apparatus for moving the headrest.
With an embodiment of the vehicle seat described above, the impact reduction member does not easily move during normal seating, which makes it possible to suppress malfunction of the impact reduction member, and the impact reduction member is stabilized. Furthermore, in a range in which the force that restores the impact reduction member into the initial state decreases when the impact reduction member moves due to a rear-end collision, the impact reduction member smoothly moves, which makes it possible to significantly move the pressure receiving member that is linked thereto and cause the occupant to sink.
In addition, it is possible to reduce impacts on the head region or the neck region by supporting the head region of the occupant, without providing a mechanism linked with the headrest for causing the headrest to move forward.
Furthermore, a mechanism or the like for transmitting loads occurring at the impact reduction member and the pressure receiving member to the headrest is not necessary, and this realizes the vehicle seat with simplicity and a lighter weight.
With an embodiment of the vehicle seat described above, the impact reduction member smoothly moves at the time of a rear-end collision, which makes it possible to significantly move the pressure receiving member and thus ensure that the occupant sinks to a high degree, as well as to make the impact reduction member more compact.
With an embodiment of the vehicle seat described above, the impact reduction member can move or rotate efficiently even when the load transmitted from the pressure receiving member at the time of a rear-end collision becomes small, and this makes it possible to ensure sinking.
With an embodiment of the vehicle seat described above, the vehicle seat with simplicity and a lighter weight compared to the prior art in which a linkage is established with the headrest. In addition, in the case where an off-balance load has occurred, the impact reduction members on the side portions on both sides move or rotate independently from each other, and thus the occupant is caused to sink in accordance with the size of the impact load. Further, the force that restores the impact reduction members into the initial state decreases along with movement of the impact reduction members. This configuration is advantageous because it makes the impact reduction members that are independent from each other move further smoothly even solely.
With an embodiment of the vehicle seat described above, the position where the engagement portions that engage the biasing element, the coupling member, and the like with the impact reduction member is disposed is selectable more freely. In addition, it makes easy to set the force by which the biasing element causes the impact reduction member to rotate to be greatest initially and gradually decrease along with the rotation. This results in the state where the impact reduction member does not easily rotate during normal seating but moves smoothly at the time of a rear-end collision.
With an embodiment of the vehicle seat described above, the portion of the seat back corresponding to the lower back region to the back region of the occupant is moved significantly backward when an impact has occurred, without interference with the various elements disposed on the outside of the seat back frame. This makes it possible to cause the occupant to sink to a sufficient extent.
With an embodiment of the vehicle seat described above, it is possible to efficiently transmit the load from the pressure receiving member that supports the body of the occupant to the impact reduction member, and thus the portion of the seat back corresponding to the lower back region to the back region of the occupant is moved significantly backward when an impact has occurred. This makes it possible to cause the occupant to sink to a sufficient extent.
With an embodiment of the vehicle seat described above, the impact reduction member is disposed in a position where the amount of sinking is large, and thus it is possible to efficiently transmit the load. Accordingly, the portion of the seat back corresponding to the lower back region to the back region of the occupant is moved significantly backward when an impact has occurred, which makes it possible to cause the occupant to sink to a sufficient extent.
With an embodiment of the vehicle seat described above, the load on the impact reduction member is transmitted efficiently in a location in which, taking the body type of the occupant into consideration, the occupant sinks the most at the time of a collision. This makes it possible to sink the lower- to mid-back region of the occupant into the seat back to a sufficient extent upon receiving an impact.
With an embodiment of the vehicle seat described above, interference with other disposed elements is preventable, and the impact reduction member is disposable using the small space more effectively.
With an embodiment of the vehicle seat described above, the impact reduction member is checkable when and after the seat back is assembled, and when the skin material has been opened.
With an embodiment of the vehicle seat described above, the operation amounts of the respective neck region impact reduction apparatuses is reduced compared to when each of the respective multiple apparatuses is used solely. Thus, the response is improved and higher degree of safety is realized.
With an embodiment of the vehicle seat described above, it is possible to operate only one of the neck region impact reduction apparatuses, such as the second neck region impact reduction apparatus, or operate the multiple neck region impact reduction apparatuses, depending on the size of the predicted impact load, or the actual collision load, and the like.
With an embodiment of the vehicle seat described above, it is possible to set the operation starting timings of the neck region impact reduction apparatuses to operation timings that facilitate suppression of a sense of discomfort imparted on the occupant. This in turn makes it possible to further reduce a sense of discomfort caused by the multiple neck region impact reduction apparatuses operating simultaneously.
With an embodiment of the vehicle seat described above, the amount of movement of the headrest is reduced, which makes it possible to move the headrest into a head region receiving position in a short amount of time. Furthermore, because the amount of movement of the headrest is reduced, a compact headrest is realizable without increasing the size of the apparatus for moving the headrest.